Rotary hydraulic cylinder

ABSTRACT

A rotary fluid pressure actuator includes a housing having an inner actuator chamber with a cylindrical side wall extending between a pair of end walls. An integral vane rotor assembly, including a shaft and end discs, is positioned in the chamber and is rotationally reciprocated in response to the direction of flow of fluid to and from chamber segments of the housing. A fixed dam is secured between flanges in an elongated opening along the cylindrical side wall of the housing, the dam extending radially into the chamber from the opening to abut against the shaft between the end discs. The dam acts as a stop to limit the reciprocal motion of the vane and shaft in each direction.

BACKGROUND OF THE INVENTION

The present invention relates to an improved construction of rotary hydraulic or fluid pressure actuator, and more particularly to an improved construction of a vane type of such actuator.

Conventional rotary fluid pressure actuators include a vane rotor assembly positioned within a sealed chamber in a housing for rotational reciprocation between positions dictated by one or more stops mounted within the housing for obstructing passage of the vane, in response to the direction of flow of fluid to and from the chamber. The vane is fixed mechanically to a shaft or the like. Hydraulic fluid pressure is exerted in sequence on the faces of the vane to rotate it and the shaft.

Such devices have numerous applications, for instance in hydraulic operation of aerial work platforms (platform bracket and jib rotation), mining equipment (carousel rotation, drill positioning, rod handling, roof bolting), refuse and recycling vehicles (articulation and cart lifting), steering and operation of components of forklift vehicles, jib crane rotation on mobile earth drilling vehicles and the like. Many types of machine tools also use such rotary fluid pressure actuators.

Such actuators are faced with many technical problems. For example, the vanes and stops are conventionally individually components mounted respectively on the shaft and on the chamber walls of the housing causing wear and distortion, as well as dislocation of these component parts and the chamber walls particularly since high fluid pressures are often involved. As well, sealing of the chamber against leakage of fluid from one side of the vane to the other, or to the outside of the housing along the shaft, is often difficult to achieve.

Prior art references of background interest include U.S. Pat. No. 4,565,119 of Higuchi, issued Jan. 21, 1986, which describes and illustrates a vane type rotary actuator in which the vane is bolted to the shaft and the stop is bolted to the chamber wall. U.S. application publication No. 2003/0126985 of Collier et al., published Jul. 10, 2003 also teaches a rotary vane actuator in which the vane is mechanically attached to the shaft. In this case, the stop is formed by a protrusion of the chamber wall into the chamber. U.S. Pat. No. 4,825,754 of Devaud et al., issued May 2, 1989, also describes and illustrates a rotary pressure actuator in which stops are formed from the chamber wall itself. U.S. Pat. No. 4,492,150 of Yates issued Jan. 8, 1985 illustrates (in FIGS. 9, 10 and 11) an internal stop which has been mounted on the casing wall for such a rotary actuator. These references, as well as U.S. Pat. No. 4,510,850 of Mack, issued Apr. 16, 1985, teach various approaches to provide better sealing for the housing chamber. U.S. Pat. No. 4,817,504 of Leiberman, issued Apr. 4, 1989, and U.S. Pat. No. 4,621,568 of Gailey, issued Nov. 11, 1986 are further examples, of general background interest, of rotary actuators.

It is an object of the present invention to provide an improved construction of rotary fluid pressure actuator which will reduce distortion of the components during operation, even at high pressures, and which will facilitate the sealing of the internal chamber against fluid leakage.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a rotary fluid pressure actuator comprising a housing having an inner actuator chamber including a cylindrical side wall extending between a pair of end walls. A shaft is centrally positioned within the chamber with respect to the cylindrical side wall, for rotation about an axis. The shaft extends through the housing. A spaced pair of end discs are provided extending radially from the shaft and integral therewith, the end discs being adjacent the end walls of the chamber. A vane extends radially from the shaft between the spaced pair of end discs, the vane being integrally associated with the shaft and end discs and the vane having opposite faces extending outwardly from the shaft to an outer edge of the vane adjacent the side wall of the chamber. An elongated opening is provided along the cylindrical side wall of the housing, with outwardly extending parallel flanges extending along sides of the opening. A fixed dam is secured between the flanges and fills the opening along the cylindrical side wall of the housing. The dam extends radially into the chamber from the opening, with an inner end lying adjacent the shaft between the end discs. The dam has a pair of opposed side surfaces which divide the chamber into a pair of chamber segments extending between each side surface of the dam and a corresponding face of the vane. A pair of fluid inlet and outlet ports are associated with the actuator for delivery to and removal of fluid with respect to each chamber segment. The vane and shaft are rotatably reciprocated within the housing, the vane abutting against the dam at its limit of reciprocal motion in each direction, in response to the pressure of fluid passed sequentially to and from the chamber segments during operation of the actuator.

In one embodiment of the present invention, the fluid inlet and outlet ports extend through the chamber side wall on each side of the dam and are adjacent thereto.

Because the vane, end discs and shaft are of unitary construction, sealing at the sides of the vane or where the vane meets the shaft, as was often required in prior art constructions, is avoided. As well, the construction of the dam, extending as it does to the shaft, provides additional support for the shaft within the chamber. Additionally, since the vane extends between and is joined to the end discs, additional support for the vane against hydraulic pressure being applied to it during operation of the device is provided.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other advantages of the invention will become apparent upon reading the following detailed description and upon referring to the drawings in which:

FIG. 1 is an exploded perspective view of an example embodiment of rotary fluid pressure actuator according to the present invention; and

FIG. 2 is a section view along line 2-2 of FIG. 1, of the actuator in accordance with the present invention;

While the invention will be described in conjunction with illustrated embodiments, it will be understood that it is not intended to limit the invention to such embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description, similar features in the drawings have been given similar reference numerals.

Turning to FIG. 1, there is illustrated, in exploded fashion, a rotary fluid pressure actuator 2 in accordance with the present invention. Actuator 2 comprises a housing 4 having an inner chamber 6 which has a cylindrical side wall 8 and end walls 10. End walls 10 are normal to the central axis of the cylindrical side wall.

A shaft 12 is centrally positioned within chamber 6 with respect to side wall 8, for rotation on that central axis. One end of shaft 14 extends beyond the corresponding end wall 10 for connection to, and driving, an appropriate work tool or machine component (not illustrated) beyond housing 4. Shaft 12 is supported within housing 4 by conventional bearings (not illustrated) which hold shaft 12 in alignment. End wall 10 acts as a shield to keep dirt and debris out of chamber 6. Formed as an integral unit with shaft 12 are a pair of spaced end discs 16 which extend radially from shaft 12, and a vane 18 which extends radially from shaft 12 as illustrated, between the end discs 16 from one to the other. The end discs 16, when in position in chamber 6, are each situated adjacent a corresponding end wall 10 of chamber 6. Vane 18 has opposite faces 20 and 22 which extend outwardly from the shaft to an outer edge 24 which is seated adjacent the side wall 8.

An elongated opening 26 extends through the housing and cylindrical side wall 8 of housing 4. Parallel, outwardly extending flanges 28 are provided on either side of the opening as illustrated. A fixed dam 30 is secured between the flanges, as illustrated, using appropriate conventional securing means such as bolting or welding. Dam 30 fills the opening 26 and extends radially into chamber 6 from that opening. Inner end 32 of dam 30 abuts against and supports shaft 12, sealing shaft 12 along its length between end discs 16. Dam 30 provides a pair of opposed side surfaces 34 and 36 which act as stops for vane 18 during its reciprocal rotative movement, as will be described in more detail subsequently. In this manner, dam 30 divides chamber 6 into a pair of chamber segments 38 and 40 extending between each of these side surfaces of dam 30 and a corresponding face 20 or 22 of vane 18.

Fluid inlet and outlet ports 42 and 44 are associated with the actuator for delivery to and removal of fluid with respect to each of these chamber segments, in the illustrated embodiment these ports extending through chamber side wall 8 immediately adjacent dam 30 on either side thereof.

In operation, it will be readily appreciated that vane 18 and shaft 12 are rotatably reciprocated within chamber 6 of housing 4, vane sides 20 and 22 abutting respectively against dam side surfaces 34 and 36 which define the limit of vane reciprocal rotation in each direction, in response to the direction of flow and pressure of fluid passed sequentially to and from chamber segments 38 and 40, through fluid ports 42 and 44, during operation of actuator 2.

Of course chamber segments 38 and 40, during that reciprocal motion, vary conversely in volume, from essentially no (or minimum) volume to maximum volume.

In the section view of FIG. 2, it will be noted that faces 20 and 22 of vane 18 are flared increasingly outwardly towards the vane's outer edge 24. Side surfaces 34 and 36 of dam 30 are contoured to conform to those that corresponding sides of the vane when vane 18 abuts against them during operation of the actuator 2. The flared construction of the sides 20 and 22 of vanes 18, providing a greater thickness and strength of the vanes towards outer edge 24, is advantageous because most of the pressure on vane 18 is applied along outer edge 24. The increased thickness of vane 18 along this outer edge 24, provided by this flared construction, helps to eliminate deflection of the vane, while at the same time facilitating transmission of most of the torque to end discs 16 and shaft 12.

The vane, disc and shaft assembly can be provided with a seal 46 between that assembly and the interior walls of housing 4 as appropriate. As well, a dam seal 48 is preferably provided, as illustrated between dam 30, shaft 12, inner surfaces of end discs 16 and the inner surfaces of flange 28.

Another feature of the rotary actuator according to the present invention lies in the fact that the portion of shaft 12 lying between end discs 16 has a smaller diameter than those portions of the shaft beyond those end discs (FIG. 1), reducing the weight of the rotating components of the actuator and increasing the volume available for fluid in the chamber segments.

The rotor construction as described above has many other advantages over prior art rotary fluid pressure actuators. For example, because of the integral, one piece construction of shaft 12, discs 16 and vane 18, the ends of the vane do not have to be sealed where the vane meets the shaft or at the sides of the vane. As well, because of this design, strength is added to the shaft as well as to the vane. The fact that the vane is integrally formed between the end discs removes most of the deflection in the shaft caused by pressure and torque during operation of the device. Moreover, the end discs transmit the torque to the shaft outside of housing 4.

Also, the construction of dam 30, and its being held in position by flanges 20, permits the dam to anchor housing 4 while at the same time it supports shaft 12, acting in this latter case as an anchor on which shaft 12 can rotate. Again, dam 30 is provided with conventional seals between itself and shaft 12, where it meets it, and end discs 16.

Thus, it is apparent that there has been provided in accordance with the invention a rotary hydraulic or fluid pressure actuator that fully satisfies the objects, aims and advantages set forth above. While the invention has been described in conjunction with illustrated embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and broad scope of the invention. 

1. A rotary hydraulic actuator comprising: (a) a housing having an inner actuator chamber including a cylindrical side wall extending between a pair of end walls; (b) a shaft centrally positioned within the chamber with respect to the cylindrical side wall, for rotation about an axis, the shaft extending through the housing; (c) a spaced pair of end discs extending radially from the shaft and integral therewith, the end discs adjacent the end walls of the chamber; (d) a vane extending radially from the shaft between the spaced pair of end discs, the vane being integrally associated with the shaft and end discs, the vane having opposite faces extending outwardly from the shaft to an outer edge of the vane adjacent the side wall of the chamber; (e) an elongated opening along the cylindrical side wall of the housing, with outwardly extending parallel flanges extending along sides of the opening; (f) a fixed dam secured between the flanges and filling the opening along the cylindrical side wall of the housing, the dam extending radially into the chamber, from the opening, with an inner end lying adjacent the shaft between the end discs, the dam having a pair of opposed side surfaces which divide the chamber into a pair of chamber segments extending between each side surface of the dam and a corresponding face of the vane; and (g) a pair of fluid inlet and outlet ports associated with the actuator for delivery to and removal of fluid with respect to each chamber segment, whereby the vane and shaft are rotatably reciprocated within the housing, the vane abutting against the dam at its limit of reciprocal motion in each direction, in response to the pressure of fluid passed sequentially to and from the chamber segments during operation of the actuator.
 2. An actuator according to claim 1, wherein the fluid inlet and outlet ports extend through the chamber side wall on each side of the dam and adjacent thereto.
 3. An actuator according to claim 1, wherein the faces of the vane are flared outwardly towards the vane's outer edge, and the opposite side surfaces of the dam are contoured to conform to the corresponding faces of the vane when the vane abuts against the dam.
 4. An actuator according to claim 2, wherein the shaft has a lesser diameter between the end discs than its diameter beyond the end discs. 